Induction-motor-regulating system



Dec. 4, 1928. I 1,694,241

W. WEILER INDUCTION MOTOR REGULATING SYSTEM Filed Nov. 21, 1925 4* 4L 1' 2/ ii 55 Qt" 4' /9 l I l3 l Fig.2.

r a l 4L ll InventoYfi His Attorney.

Patented Dec. 4, 1928.

UNITED STATES PATENT OFFICE.

WILHELM NEILER, OF NIEDERSCHONHAUSEN, GER-MANY, ASSIGNOR TO GENERAL ELECTRIC COMIANY, A CORFORATION OF NEW YGRK.

INDUCTIONMOTOR-REGULATING SYSTEM.

Application filed November 21, 1925, Serial No. 70,634, and in Germany December 1.0, 1924.

My invention relates to the speed control of induction motors, and in particular to means for increasing the slip of induction motors with load, atthe same time providing desirable power factor correction.

My intention particularly adapted to an induction motor drive installation where it is desired to take advantage of fly-wheel effect in smoothing out the load ta en from the alternating current supply U em with varying loads on the installation.

In carrying my invention into effect, I employ a coinmi'ltatoi' machine which is driven synchronously with the main motor. The commutator machine has stator and rotor windings conno rd in series with the secondary of the main motor and these which are so arranged as to neutralize the effect of the secondary current flowing therein. The rotor winding of the commutator ma chine is also energized by a voltage proportional to the primary load current of the main motor and at such a phase angle as to provide the desired power factor correction. This ar- J1 rangcment permits the speed or the outfit to materially decrease with load while maintaining power factor correction.

The features of my invention which are believed to be novel and patentable will be pointed out in the claims appended hereto. For a better understanding of my invention, reference is made in the following description to the accompanying drawing in which Fig. 1 shows the mechanical arrangement of a preferred embodiment of my invention, and Fig. 2 illustrates the electrical connections for this arrangement.

Referring to the drawing, in Fig. 1., represents the main induction motor, the stator of which is supplied from the power supply line 11. 12 represents a flywheel, and 13 represents any variable load macl'iinc to he driven by the motor 10. 1+1 represents a coin-- inutator machine having stator windings 15 and a commutator winding 16 (see Fig. :2) conluwtcd in series with the secondary winding 16 of the main induction motor 10 through the slip rings 17 and loads 18. As shown in Fig. 1, the commutator machine 14-. is mounted on the same shaft 19 with the main motor 10, fly-wheel 12, and the load machine 13, and has the same number of poles as 10. An equivalent geared arrangement may be used.

In Fig. 2 the primary of the main motor is represented at 20, and in series with its supply lines is a transformer 21, the secondary of which is connected to the commutated winding 16 by way of leads 22 and slip rings 23.

The stator winding 15 and the rotor wind ing 16 of machine 14 are arranged so that the effect of the current flowing in series therethrough from the secondary of motor 10 is neutralized, or substantially neutralized. Another way of stating this is to say that the rotor and stator fields produced by this current compemiate and nullify each other without producing either torque or generator action. This may be readily accomplished by properly proportioning the two windings giving them the sa 1e resultant phase rotation and properly positioning the commutator brushes. However, the rotor winding 16 re ceives additional excitation from the transformer 21 which excitation is proportional to the primary current of the main motor. This additional excitation produces a resultant field in the commutator machine which is )roportional to the primary current of the main motor and independent of its secondary current.

The sum of the electromotive forces generated in the commutator machine thus depends only upon the primary load current and the speed of the machine. The phase angle of this additional excitation is also made such as to provide the desired power factor correc tion for the main motor and may be properly adjusted in any convenient way, as, for example, by a change in the coupling angle at the coupling represented at 2 1.

It will be readily seen that if the motor load tends to increase, the excitation of machine 14; from the transformer 21 will increase and tend to decrease the motor load. wil allow the speed to decrease to such an cut that a large part of the additional load will be carried by the Fly-wheel. The motor is thus caused to have series characteristics which may be made as strong as desired by the proper selection or adjustment of the transformer 21. The circuits of machine 1% may he of relatively low resistance. The energy given out by the secondary of motor 10 is for the most part utilized in operating machine le as a motor which is made possible by the additional excitation from transformer 21.

In accordance with the provisions of the 9 This patent statutes, 1 have described the principio 'hcr 'th the apparatus which I now con sent the best cmbodimen sire to have it under o shown and des other means.

hat 1 claim by Letters Pate 1. In con'ibiinition. on having; 21 form wound sccon; ,r commutator 111;1Ci'liDC- driven in with said induction 'nuch tii'ely inovnbic con ings co "cd. i

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i 1 or 0::- citing' the con nmt"9'- oi 7 id con mutntor machine b 1 it proportional to the prin or; current of sirid inthiction mm chine, the phmc ungie of said excitation being such as to inciude the pow-or factor ot said induction machine.

2 In combination, an induction motor barring a form wound secondary rinding, u commut-utor machine having the same number of polea as said motor and driven directly therewith, field windin on said commutator nnichine connected in with the commutzitcd winding; thereof and with the secondziri' windin off said in d uction i'notor, the windnfgu of said commutator machine being ot so as to snbscnntiniiy compensate who 'zuch that in so far; he how thereeconthiry cnrrcnt oi the induction zione is onccrnod neither motor nor tor 11 tion would )0 produced in such rtztef. machine u s rios truns circuit of mid inducnihiing excitation to the d :oinmntntor nv' of the now-or factor oi mid v the pun:

oto

(tint-as whereof, I ha fic hereunto SCt my hand this 25th duv (At October 1925.

IL? ELM TUEILE R. 

